The simulation of the satellite rotational dynamics on a three-degrees of freedom (DOF) spacecraft simulator has always been limited by the maximum angle of rotation allowed by the spherical air bearing. A number of different three-axis spacecraft simulators based on spherical air bearing have been developed so far, but none of them allows a full 4π steradians rotation.
This limitation of the spherical air bearing reduced the effectiveness of the experimental validation of spacecraft rotational dynamics, for instance, large angle maneuvers or detumbling cannot be fully tested on standard spacecraft simulator.
What is needed is a method of eliminating the constraint on the maximum rotation angle, whereby a complete ground testing of the spacecraft attitude determination and control techniques will be possible.